trailer with lowerable and raisable trailer bed

ABSTRACT

A trailer including: i) a draw bar; ii) a trailer frame supporting a trailer bed; iii) an arm including a first pivot mount; iv) an axle pivotally connected to the arm at the first pivot mount; v) an actuating mechanism actuatable to exert a force on the arm relative to the trailer frame. The axle includes at least one associated wheel and the wheel has a plane of rotation in which the wheel rotates when traveling in a forward direction, and the actuating mechanism is located substantially in the plane of rotation. The trailer bed may be raised or lowered by exerting a force on the arm relative to the trailer frame.

TECHNICAL FIELD

The present invention relates to trailers and more particularly, but notexclusively to trailers which can be used to transport vehicles. Theinvention is described herein in relation to trailers for transportingvehicles but the apparatus and method may be used in relation to othertypes of trailers such as caravans, horse floats or trailers for movingequipment, furniture etc.

BACKGROUND OF THE INVENTION

Trailers are known to be used to transport cars and other vehicles. Forexample, they can be used to transport racing cars from one place toanother. There are various problems associated with the existingtrailers.

Generally, existing trailers are provided with ramps that are deployedsuch that a vehicle can be driven or winched onto the trailer. There isalways a chance of damage to the front portion of the vehicle when it isdriven or winched onto the trailer because there is not sufficientclearance between the front portion and the ramps. The problem iscompounded when loading vehicles which have lower ground clearance suchas racing cars.

In some trailers, the trailer beds have an extendable trailing end andthe trailing end of the trailer can be extended and lowered such thatthe trailing end of the trailer provides the slope for the vehicle to bedriven or winched onto the trailer. However, generally the trailing enddoes not touch the ground and there is a clearance between the trailingend and the ground. Once the vehicle is in position on the extendedtrailing end of the trailer bed, the trailing end is retracted andraised. However, this does not rule out the possibility of damage to thevehicle when being driven or winched since the vehicle still has toovercome the slope. Further, such an extension and tilting arrangementoverloads the axle.

Generally, trailers with extendable trailer beds require tandem axles tosupport the additional weight and tilting action of the extensionportion (trailing end). Inclusion of tandem axles adds to the weight ofthe trailer. Also, tandem axle trailers are difficult to manoeuvrearound sharp corners and pose significant problems in transportation.

Further, while loading racing cars onto most existing trailers, it isrequired to remove the low front spoiler so that damage to the frontspoiler is averted. Removing and securing the front spoiler necessitatesadditional time and efforts of the individuals loading the car.Commonly, more than one individual is required to load and unload therace car from the trailer.

Use of ramps or extendable trailer beds is also inconvenient for otherkinds of loads, such as furniture, horses, wheelchairs, tools ormachinery, as the load must be manually pushed/lifted (or led) up theramp or trailing end. This can be both awkward and heavy, and results inincreased risk of accidents and lower safety standards, in addition topotentially requiring more people to assist with loading. Caravans aregenerally provided with folding steps to be climbed by users, which isinconvenient for the elderly or disabled. Ramps may be retrofitted butremain inconvenient.

With the aforementioned in mind, the present invention seeks toalleviate one or more short comings of such known prior art in providinga trailer that reduces the risk of damage to the load (eg vehicle) whenloading and unloading, simplifies loading and unloading and improvessafety.

Reference to any prior art in the specification, whether in thebackground section or otherwise, is not, and should not be taken as anacknowledgement or any form of admission that the prior art forms partof the common general knowledge in Australia.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides a trailer including:

i) a draw bar;

ii) a trailer frame supporting a trailer bed;

iii) an arm, the arm including a first pivot mount;

iv) an axle, the axle being pivotally connected to the arm at the firstpivot mount;

v) an actuating means, the actuating means being actuatable to exert aforce on the arm relative to the trailer frame;

wherein the axle has at least one associated wheel and the wheel has aplane of rotation in which the wheel rotates when traveling in a forwarddirection, and the actuating means is located substantially in the planeof rotation;

whereby the trailer bed may be raised or lowered by exerting a force onthe arm relative to the trailer frame.

Advantageously, the trailer bed may be lowered flat to the ground forloading and unloading. This makes the process easier and safer thanloading, for example, using a ramp, forklift or other method. It alsoreduces the likelihood of damage to the load, for example, damage to thespoiler of a race car, as a race car has a low clearance and thusproblems with loading up a ramp.

Advantageously, this also allows for a neat and compact system forraising and lowering the trailer, maximising the load carrying space andminimising the outer dimensions of the trailer.

Preferably the first pivot mount is located inwardly of the wheel.Preferably, the actuating means exerts the force on the arm at alocation substantially in the plane of rotation.

In one embodiment the actuating means exerts the force on the arm at alocation forward of the wheel and in another embodiment the actuatingmeans exerts the force on the arm at a location rearward of the wheel.

In one preferred embodiment the arm is pivotally connected to the axleat a location inwardly of the wheel and the actuating means acts on aportion of the arm at a location substantially in the plane of rotation.

In one preferred embodiment the trailer frame includes a second pivotmount, the arm being pivotally movable relative to the trailer frameabout the second pivot mount. Preferably the second pivot mount islocated substantially in the plane of rotation. In one embodiment, theactuating means exerts the force on the arm at a location forward of thesecond pivot mount and in another embodiment the actuating means exertsthe force on the arm at a location rearward of the second pivot mount.

In one embodiment of the trailer, the arm has at least two portionswhich are angled relative to each other when projected on the plane ofrotation.

Preferably the arm has at least two portions which are angled relativeto each other when projected onto a substantially horizontal planeperpendicular to the plane of rotation.

In another embodiment the arm may have at least a first section and asecond section, the first and second sections being in slideableengagement.

In a preferred embodiment the trailer frame includes a third pivot mountlocated higher than and rearward of the second pivot mount, theactuating means pivotally mounted to the third pivot mount andactuatable to exert a force on the arm resulting in rotation of the armabout the second pivot mount.

In another embodiment the trailer frame includes a fixed point locatedhigher than and forward of the second pivot mount, the actuating meansactuatable to exert a force between the fixed point and the arm,resulting in rotation of the arm about the second pivot mount.Preferably the fixed point is provided by a bracket.

Selecting optimal geometry advantageously allows the actuation means tobe positioned to obtain maximum leverage, and hence requires less forceto raise or lower the trailer.

Preferably the trailer further includes a draw bar pivot mount, the drawbar pivotally connected to trailer frame via draw bar pivot mount.

Advantageously this allows the trailer to be raised or lowered withoutneeding to unhitch the trailer from the towing vehicle, and preventsoverloading of the tow vehicle draw bar during loading/unloading.

Preferably the actuating means is a first airbag.

In one embodiment the trailer further includes a spring and an airvalve, the valve being operable to deflate first airbag and the springbiasing the draw bar towards a towing position. In an alternativeembodiment, the trailer includes a draw bar bracket mounted on the drawbar, a connecting bracket mounted on the trailer frame, and a secondairbag extending between the draw bar bracket and the connectingbracket, the second airbag when inflated positioning the draw bar in atowing position. Preferably the first and second airbags have a commonfirst isolating valve and a common venting valve, whereby they are heldat a common pressure. This can improve safety and also assists to avoidoverloading of the tow bar.

Preferably the trailer further includes brakes associated with the wheeland a safety brake interlock switch operable to prevent the wheel fromturning when the draw bar is not in a towing position. This can alsoimprove safety.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of one or more preferred embodiments ofthe present invention will be readily apparent to one of ordinary skillin the art from the following written description with reference to and,used in conjunction with, the accompanying drawings showing preferredembodiments of the invention, in which:

FIG. 1 shows a side view of a towing vehicle with a trailer according toa first embodiment of the invention in the towing position; and

FIG. 2 shows a side view of a towing vehicle with trailer according tothe embodiment of FIG. 1 in an intermediate unloading position; and

FIG. 3 shows a side view of a towing vehicle with trailer according tothe embodiment of FIG. 1 in a lowered or unloading position; and

FIG. 4 shows a top plan view of a towing vehicle with trailer accordingto the embodiment of FIG. 1; and

FIG. 5 shows a side view of a portion of the trailer according to theembodiment of FIG. 1 in a raised or towing position; and

FIG. 6 shows a side view of a portion of the trailer according to theembodiment of FIG. 1, in the lowered or unloading position; and

FIG. 7 shows a top plan view of a towing vehicle with trailer accordingto another embodiment of the invention; and

FIG. 8 shows a side view of a portion of the trailer of FIG. 7, in theraised or towing position; and

FIG. 9 shows a side view of a portion of the trailer of FIG. 7, in thelowered or unloading position; and

FIG. 10 shows a side view of a draw bar arrangement for a traileraccording to an embodiment of the invention, in the raised or towingposition; and

FIG. 11 shows a side view of the draw bar arrangement of FIG. 10 in aposition corresponding to FIG. 2; and

FIG. 12 shows a side view of the draw bar arrangement of FIG. 10 in thelowered or unloading position; and

FIG. 13 shows a side view of the draw bar arrangement of FIG. 10 in anupright position for parking or storage; and

FIG. 14 shows a side view of arrest means for a trailer according to apreferred embodiment of the invention; and

FIG. 15 shows a side view of the arrest means of FIG. 14 in analternative position; and

FIG. 16 shows a side view of a draw bar arrangement for a traileraccording to another embodiment of the invention, in the raised ortowing position; and

FIG. 17 shows a side view of the draw bar arrangement of FIG. 16 in thelowered or unloading position; and

FIG. 18 shows a side view of the draw bar arrangement of FIG. 16 in anupright position for parking or storage; and

FIG. 19 shows a schematic plan of the pneumatic circuit for theembodiment of FIGS. 16 to 18.

DESCRIPTION OF PREFERRED EMBODIMENT

FIGS. 1 to 3 show side views of a towing vehicle (5) together with atrailer (10) according to a first embodiment of the invention. FIG. 1shows the trailer (10) in the towing position, FIG. 2 shows the trailer(10) in an intermediate position and FIG. 3 shows the trailer (10) in aloading position, for loading or unloading a race car (6). It is notedthat the trailer (10) is suited to carrying many other types of loads ina similar manner.

FIG. 4 shows a plan view of the trailer of FIGS. 1 to 3. Referring toFIGS. 1 to 4, the trailer (10) includes a trailer frame (15) whichsupports a trailer bed (16) upon which a load, race car (6), rests. Adraw bar (12) connects the trailer frame (15) to a towing vehicle (5).The trailer (10) further includes a stub axle (24) having an associatedwheel (22). The trailer (10) shown in FIGS. 1 to 4 has one pair ofwheels mounted on stub axles, however other wheel arrangements such astandem axles lie within the scope of the invention.

To load or unload the trailer (10), the trailer bed (16) isadvantageously lowered substantially level with the ground (7), as shownin FIG. 3. This lowering action is enabled by a raising and loweringmechanism that includes a pivoting arrangement between axle (24) andtrailer frame (15). The ability to lower the trailer (10) to a positionsubstantially level with the ground (7) without disconnecting draw bar(12) from towing vehicle (5) is enabled by a pivoting arrangementbetween draw bar (12) and trailer frame (15). The draw bar (12) isconnected to and triangulated to the front or forward end of the trailerframe (15)—unlike prior art trailers where the draw bar triangulationmay extend below the frame (15). This advantageously allows the trailerframe (15) to be lowered to the ground (7) as the draw bar triangulationis not in the way. Use of the term ‘lay-flat’ indicates that the traileris lowered to achieve a substantially horizontal orientation of thetrailer bed at a height substantially level with the (horizontal)ground. Substantially level with the ground includes circumstances wherethe trailer 10 retains a small clearance between the underside of thetrailer bed and ground but which still allow for normal walking orrolling of loads onto the trailer bed without making an effort such aslifting or stepping up a step.

Hence, as shown in FIGS. 1 to 3, the trailer (10) may be lowered fromthe towing position of FIG. 1 to the intermediate position of FIG. 2, inwhich the rear end of trailer (10) rests substantially level with or onthe ground (7). The trailer (10) is then lowered to the loading positionof FIG. 3, in which the front end of trailer (10) also restssubstantially level with or on the ground (7). The trailer (10) may beconveniently loaded or unloaded and the process carried out in reverseto raise the trailer (10) into the towing position of FIG. 1.

FIGS. 5 and 6 show side views of a part of the trailer (10) of FIGS. 1to 4. The pivoting arrangement provided on the left side of the trailer(10) between axles (24) and trailer frame (15) is provided by an arm(30) which includes a first pivot mount (36) to which axle (24) ispivotally connected. The left side including airbag (44) will bedescribed below, however it is noted a mirror image arrangement providedon the right side of the trailer including airbag (44′) is also shown inFIG. 4. However a mirror image arrangement is not essential. The trailerframe (15) includes a second pivot mount (20) to which the arm (30) ispivotally connected. It is noted that the pivot mounts mentioned hereincould be holes, recesses, rods, pins, bars etc which allow for pivotalconnection. Wheel (22) rests upon ground (7) and has a plane of rotationin which the wheel (22) rotates when the wheel (22) and trailer (10) aretravelling in a forward direction, ie a vertical plane extending in thedirection from the front to the rear of the trailer.

Use of the term ‘in-line’ in this document refers to something located,positioned or acting at a point that is in-line with one of the trailerwheels, that is, located positioned or acting at a point on the plane ofrotation in which the wheel rotates when travelling in a forwarddirection. Use of the terms ‘in-line’ or ‘plane of rotation of thewheel’ is not to indicate or restrict to a specific one of many parallelplanes of rotation, but rather is to include any one of the manyparallel planes of rotation of the wheel, as the wheel has a thicknessresulting in, for example, an inner side plane of rotation, acentre-line plane of rotation and an outer-side plane of rotation. Thewheel also has a plurality of other parallel planes of rotation.

Inner-side (23′), centreline (23) and outer-side (23″) planes ofrotation are partially shown in plan view in FIG. 7 as dotted linesextending from the forward end of the trailer (10′), in line with thewheel (22′). On some trailers (not shown) the wheels may be steerable,or mounted on an axle that can pivot in response to turning corners orthe like. In such a case, while actually turning the corner or beingsteered, the plane of rotation of the wheel is not the same plane ofrotation in which the wheel rotates when travelling in a forwarddirection, as the trailer is not travelling in a forward direction (i.e.straight ahead) but rather is travelling around a corner. Unless contextindicates otherwise, the ‘plane of rotation of the wheel’ is the planein which the wheel rotates when the trailer is travelling in a forwarddirection, straight ahead. Referring again to FIGS. 5 and 6, the heightof trailer frame (15) relative to the wheel (22) and ground (7) may beadjusted via the pivoting of arm (30) relative to axle (24) and trailerframe (15). For the left hand side, as viewed in the side views of FIGS.5 and 6, the arm (30) rotates counter-clockwise about the second pivotmount (20) as the trailer is lowered from the view of FIG. 5 to the viewof FIG. 6, and rotates clockwise about the second pivot mount (20) asthe trailer is raised.

The use of the term “trailer frame” herein includes components ofequivalent function for trailers not having a chassis, for example“non-chassis caravans” in which various components may serve a doublepurpose, e.g. act as both a side wall panel and as a part of the frameor structure supporting the trailer bed (or floor of a caravan).

As shown in FIG. 4, the end of the arm (30) connected by first pivotmount (36) to the axle (24) is disposed inwardly of the wheel (22), andthe other end of the arm (30) connected to the second pivot mount (20)is disposed in-line with the wheel, i.e. in the plane of rotation of thewheel (22).

In one embodiment the arm (30) has at least two portions which areoffset from and preferably angled relative to each other when projectedon the plane of rotation of the wheel (22). This projection showing therelative offset and angles may be as viewed in FIGS. 4 to 6.

The embodiment of FIGS. 1 to 6 has an arm (30) having a first portion(37), a second portion (38) and third portion (39). Each portion isangled relative to the other two portions when projected onto the planeof rotation, as shown in the side views of FIGS. 5 and 6. However, thearm could extend in a ‘straight’ line when projected onto the plane ofrotation.

The first portion (37) is pivotally connected via the second pivot mount(20) to trailer frame (15). The third portion (39) is pivotallyconnected via the first pivot mount (36) to the axle (24).

The trailer frame (15) includes a third pivot mount (42) to which anactuating means (40) is pivotally mounted. The actuating means (40) isan inflatable airbag (44) which could be run by an air compressor (43).The air compressor (43) may conveniently be stored or positioned in-linewith wheel (22) that is, at a location substantially in the plane ofrotation of the wheel. Alternative actuating means including mechanical,other pneumatic or hydraulic actuators could also be used. The airbag(44) may be actuated to exert a force between the second portion (38) ofarm (30) and the trailer frame (15) at a location substantially in theplane of rotation of the wheel.

In the embodiment shown in FIGS. 4 to 6, the lower end of the airbag isfixed to second portion (38) and hence in a given actuation position theairbag (44) maintains a fixed distance between the second portion (38)and the third pivot mount (42). Hence, the angle at which the firstportion (37) is mounted at the second pivot mount (20) is also fixed, asthe second pivot mount (20) and third pivot mount (42) are both mountedon trailer frame (15) and in fixed positions relative to each other. (Inalternative embodiments, not shown, the airbag is not fixed to the arm,it instead maintains a minimum distance between the arm and pivot mount,rather than a fixed distance.)

In the embodiment of FIGS. 4 to 6, as the arm (30) is held at a fixedangle (for a given actuation position) at second pivot mount (20), thethird portion (39) of the arm is also held at a fixed position relativeto the trailer frame (15). Thus the trailer frame (15) is maintained ina fixed position relative to the axle (24). The axle (24) is mounted toarm (30) via the first pivot mount (36) and the wheel (22) is mounted tothe axle (24) and hence the trailer frame (15) is maintained in a fixedposition relative to ground (7) upon which wheel (22) is supported (fora given actuation position). Referring to FIG. 5, the actuation positionof the airbag (44) is the extended position and the trailer frame (15)is held clear of the ground (7) in the towing position. Referring toFIG. 6, the actuation position of the airbag (44) is the retractedposition and the trailer frame (15) rests substantially level with theground (7). The airbag (44) passes through intermediate actuationpositions as the trailer (10) is raised or lowered. The shape of arm(30), having three portions inclined (when projected onto the plane ofrotation) to form a “curved” arm, advantageously provides additionalspace in which to position the actuating means, when compared to an armwhich extends in a straight line. This enables the neat and convenientpackaging of the raising and lowering mechanism in the verticaldirection. In the embodiment shown in FIGS. 1 to 6, the raising andlowering mechanism (including arm 30 and actuation means 40) does notprotrude above the top of wheel (22).

Nor does the raising and lowering mechanism protrude below trailer frame(15) when in the lowered position. Thus the trailer (10) may lay flat tothe ground as the arm (30) and actuation means (40) move out of the wayas the trailer is lowered. In the embodiment of FIGS. 1 to 6, theactuation means (40) being airbag (44) is fixed to third pivot mount(42) on frame (15). Third pivot mount (42) is located on frame (15) at apoint which is higher and rearward of the second pivot mount (20). Theheight of the airbag (44) in its retracted position, the heightdifference on frame (15) of third pivot mount (42) and second pivotmount (20) and the distance rearward of third pivot mount (42) fromsecond pivot mount (20), in combination with the “curvature” of arm (30)may be selected to create a suitable geometry in which inflating theairbag (44) to an extended position causes the frame (15) to be raised asuitable distance into the towing position.

The third pivot mount (42) is located with sufficient height above thelower surface of the trailer frame/bed 15, 16 and thus the top ofactuation means (40) does not interfere with laying the trailer flat. Inthe embodiment shown the third pivot mount (42) is on a side member offrame (15). The bottom of actuation means (40) can move clear of theground (7) to allow the lay flat position as the bottom of actuationmeans (40) rests upon or is connected to the arm (30) and the arm (30)rotates out of the way of the ground (7) as the trailer (10) is laidflat.

The airbag (44) will not interfere with the load as it is located to theside of the main or useful load carrying area in a position in-line withthe wheel (22).

Desirably the arm (30) has at least two portions which are offset fromand preferably angled relative to each other when projected onto ahorizontal plane perpendicular to the plane of rotation ie a horizontalplane. This projection showing the offset and relative angles may beviewed in the plan view of FIG. 4. The embodiment of FIGS. 1 to 6 hasthree portions, with the two end portions angled relative to the middleportion. The two end portions are not angled relative to each other butare offset. It would be possible to provide an arm having two offsetportions connected directly to each other, without an angled middleportion.

The neat and convenient packaging of the raising and lowering mechanismis also improved by the shape of arm (30) when projected onto the planeperpendicular to the plane of rotation. Referring to the plan view ofFIG. 4, the arm (30) has a first portion (37) positioned in line withthe wheel (22), ie on the plane of rotation, a second portion (38) onwhich the airbag (44) exerts a force, the second portion (38) angledrelative to the first portion (37) and a third portion (39) parallel tobut offset from the first portion (37), onto which the wheel (22) ismounted via first pivot mount (36). Hence, the raising and loweringmechanism has minimal impact on the overall width of the trailer (10) orthe available or useable space on trailer bed (16), as part of themechanism is positioned in the plane of rotation, ie in line with thewheel (22). In particular the relatively bulky airbag (44) is positionedin line with the wheel (22).

The National Code of Practice for building small trailers in Australiaspecifies that the maximum width of trailers used for carrying cars mustnot be greater than 2.5 metres. This restriction on the maximum width ofthe trailers means that any added features to overcome prior artproblems should not increase the overall width of the trailer, anddesirably should also not adversely affect available useful load space.

In an alternative embodiment, as shown in FIGS. 7 to 9, the actuationmeans (40′) is positioned in an alternative location. The pivotingarrangement between axle (24′) and trailer frame (15′) is provided byarm (30′) which includes first pivot mount (36′) to which axle (24′) ispivotally connected. The trailer frame (15′) includes a second pivotpoint in the form of a pin, rod or bar (48). The pivot point could beprovided in other forms in alternative embodiments. The arm (30′) restsupon the pin (48) and may slide and rotate relative to the pin (48). Inthe embodiment of FIGS. 7 to 9, the trailer frame (15′) includes abracket (47) which is connected to the trailer frame (15′) by pin (48)and held in fixed position relative to the trailer frame (15′). However,it is noted that the bracket (47) could be welded or otherwise connectedto the trailer frame (15) in alternative embodiments, without contactingthe pivot point ie pin (48).

The bracket (47) supports actuation means (40′) being an airbag (44′).The airbag (44′) may be actuated to exert a force on a first section(32) of arm (30′) relative to the trailer frame (15′). In the embodimentshown in FIGS. 8 and 9 the lower end of airbag (44′) is fixed to bracket(47) and hence in a given actuation position the airbag (44′) maintainsa fixed distance between the first section (32) and the bracket (47).Hence, the angle at which the arm (30′) rests upon the pin (48) is alsofixed. As the arm (30′) rests on pin (48) at a fixed angle (for a givenactuation position), the arm (30′) is also held at a fixed positionrelative to trailer frame (15′). Thus the trailer frame (15) ismaintained in a fixed position relative to the axle (24′). The axle(24′) is mounted to arm (30′) via the first pivot mount (36′) and thewheel (22′) is mounted to the axle (24′) and hence the trailer frame(15′) is maintained in a fixed position relative to ground (7′) uponwhich wheel (22′) is supported. The raising and lowering mechanismincluding arm (30) and actuation means (40′) does not protrude belowtrailer (10) when in the lowered position, allowing the trailer to layflat. In this embodiment, this has been achieved by providing a fixedpoint (bracket 47) on which actuation means 44′ acts and does notprotrude substantially below the trailer (10). In the lowered positionof FIG. 9, the trailer has been lowered substantially level with theground 7′ but retains a small clearance between trailer and ground. Thisstill enables a load to easily walk or roll onto the trailer bed but maybe desirable for usage situations where the ground 7′ itself is notlevel and even. The trailer is supported by the wheel and bracket (47)with a small clearance between the ground (7) and trailer bed (16). Anyunevenness of the ground will be less likely to transmit a point loadthrough an inappropriate location e.g. the centre of the trailer bed.

The arm (30′) of FIGS. 7 to 9 may be a rigid single piece arm, or itcould include a first section (32) and a second section (34) which canslide relative to each other. In one embodiment of FIGS. 7 to 9, thefirst and second sections (32, 34) are arranged in sliding engagement,and it is the first section (32) which rests on pin (48). However, thesliding engagement could be arranged such that the second section (34)rests on the pin (48). The sliding engagement could be telescopic.

When projected onto the plane of rotation of the wheel (22′), the firstsection (32) and second section (34) form a straight line. The firstsection (32) of the arm is disposed substantially in the plane ofrotation of the wheel, and the second section (34) extends alongside thefirst section (32) in a plane parallel to and inwardly of the plane ofrotation of the wheel. The arm (30′) includes a third section (35)angled relative to the second section (34). The third section (35)includes pivot mount (36′) to which axle (24′) is connected, and isdisposed inwardly of the wheel (22′).

The airbag (44′) may be actuated to exert force on the first section(32) and, as the angle at which first section (32) rests on pin (48) isadjusted by this actuation, the first section (32) may slide relative topin (48) and relative to second section (34). As the angle at which thefirst section (32) rests on pin (48) is adjusted, so is the angle ofthird section (35) relative to the first pivot mount (36′).

Referring to the plan view of FIG. 7, the shape of arm (30′) whenprojected onto the plane perpendicular to the plane of rotation isshown. Similarly to the embodiment of FIG. 4, the arm (30′) has a firstsection (32) on which the airbag acts positioned in line with the wheel(22′), ie on the plane of rotation, a second section (34) and a thirdsection (35) offset from the first section (32) and pivotally connectedto the axle (24′) at a location inwardly of the wheel (22′). Hence theraising and lowering mechanism has minimal impact on the overall widthof the trailer (10′) or the available or useable space on trailer bed(16′).

To enable the trailer (10) to be raised or lowered without disconnectingthe trailer (10) from the towing vehicle (5), a pivoting arrangement maybe provided between draw bar (12) and trailer frame (15). Referring toFIGS. 10 to 14, there is shown a first embodiment of such anarrangement, including a draw bar (12) having a front or first end (13)which may be connected to a towing vehicle via hitch mechanism (11). Thedraw bar (12) has a rear or second end (14) which includes draw barpivot mount (71). The trailer frame (15) is pivotally connected to thedraw bar (12) via draw bar pivot mount (71). As shown in the towingposition of FIG. 10, trailer frame (15) has a connecting bracket (70)into which the end (14) of draw bar (12) is received and to which it ispivotally connected via draw bar pivot mount (71). The connectingbracket (70) supports draw bar (12) in a horizontal position and limitsthe range of rotation, or degree to which the draw bar (12) may bepivoted, relative to the trailer frame (15).

An onboard air compressor system may be provided and as shown in FIGS. 4and 7, an air compressor 43, 43′ may be located in line with wheel 22,22′, as may an accumulator compartment.

Preferably the air compressor (43) and hence airbag (44) is operatedusing controls located on or near draw bar (12). The airbag (44) may beoperated or inflated to standard pressures such as 70-90 psi.

Shown in FIG. 10 is part of trailer frame (15) connected via connectingbracket (70) and pivot mount (71) to draw bar (12). Mounted on draw bar(12) is a draw bar bracket (65) having bracket pivot mount (65′). Aclamp bar (66) is pivotally connected to the draw bar bracket (65) viabracket pivot mount (65′). Clamp bar (66) supports a cover or housing(60) which may be opened by rotating about pivot mount (65′) to allowaccess to the controls of controlling the air compressor (43). To openthe cover (60), a T-bolt (67) may be loosened to release clamp bar (66)from connecting bracket (70). FIG. 10 shows the raised or towingposition, with the cover (60) in the closed position. In FIG. 11, thecover (60) has been opened and a safety brake interlock switch (62)thereby closes, providing supply to the trailer brakes associated withwheel (22) to prevent movement of the trailer (10). Preferably thesafety brake interlock switch closes when T-bolt (67) is loosened.

Supported between draw bar bracket (65) and connecting bracket (70) is aspring air valve (85) which may be opened to release air from the airbag(44).

Valve (85) is pivotally connected to draw bar bracket (65) at a firstvalve pivot mount (86) and pivotally connected to connecting bracket(70) at a second valve pivot mount (87). The spring air valve (85) isprovided as an assembly but could be provided as a separate spring andseparate valve.

An air connecting line (not shown) connects the valve (85) to the aircompressor (43) and accumulator compartment and hence to airbag (44). Asshown in FIG. 12, as air is bled from airbag (44) via valve (85),trailer frame (15) is lowered (hitching mechanism (11) remains at itsoriginal height) and draw bar (12) pivots clockwise about draw bar pivotmount (71). At the same time, valve (85) pivots about the valve pivotmounts (86, 87).

The spring (84) in spring air valve (85) acts to try to counteract thisclockwise pivoting of the draw bar (12). This safety feature biases thedraw bar (12) towards a safer ‘towing’ position should T-bolt (67) andclamp bar (66) not be correctly engaged such that the draw bar (12) ishorizontal and fixed in relation to trailer frame (15).

Once the trailer bed (16) has been lowered to the ground (7) the load(6) may easily be removed. To raise the trailer back to the towingposition, airbag (44) is re-inflated from an air source such as abottle, air compressor or accumulator chamber. As air bag (44) isinflated, draw bar (12) returns to a horizontal position and cover (60)may be replaced, clamped using clamp bar (66) and T-bolt (67) fastenedand safety interlock disengaged.

FIG. 13 shows a draw bar (12) stowed in an upright position, allowingfor an unhitched trailer to be positioned in a smaller area. This isuseful for storage of the trailer (eg in a garage) or for parking thetrailer at a race event, whether or not the race car remains loaded. Thespring air valve (85) is disconnected from the connecting bracket (70).Provision of hole (77) provides convenient method of locking draw bar(12) in an upright position by insertion of a pin (not shown) to holdthe draw bar (12) in place.

A preferred second embodiment of a pivoting arrangement may be as shownin FIGS. 16 to 18. There is shown a draw bar (12) having a front orfirst end (13) which may be connected to a towing vehicle via hitchmechanism (11). The draw bar (12) has a rear or second end (14) whichincludes draw bar pivot mount (71). The trailer frame (15) is pivotallyconnected to the draw bar (12) via draw bar pivot mount (71). As shownin the towing position of FIG. 16, trailer frame (15) has a connectingbracket (70) into which the end (14) of draw bar (12) is received and towhich it is pivotally connected via draw bar pivot mount (71). Theconnecting bracket (70) supports draw bar (12) in a horizontal positionand limits the range of rotation, or degree to which the draw bar (12)may be pivoted, relative to the trailer frame (15).

An onboard air compressor system may be provided and as shown in FIGS. 4and 7, an air compressor 43, 43′ may be located in line with wheel 22,22′, as may an accumulator compartment.

Preferably the air compressor (43) and hence airbag (44) is operatedusing controls located on or near draw bar (12). The airbag (44) may beoperated or inflated to standard pressures such as 70-90 psi.

Shown in FIG. 16 is part of trailer frame (15) connected via connectingbracket (70) and pivot mount (71) to draw bar (12). Mounted on draw bar(12) is a draw bar bracket (65).

Supported between draw bar bracket (65) and connecting bracket (70) isan air spring being second airbag (85′) which is pivotally connected todraw bar bracket (65) at a first airbag pivot mount (86′) and pivotallyconnected to connecting bracket (70) at a second airbag pivot mount(87′). As air is bled from airbag (44) trailer frame (15) is lowered(hitching mechanism (11) remains at its original height) and draw bar(12) pivots clockwise about draw bar pivot mount (71). At the same time,second airbag 85′ deflates and pivots about the airbag pivot mounts(86′,87′). Second airbag 85′ when inflated biases the draw bar (12)towards a safer ‘towing’ position such that the draw bar (12) ishorizontal and fixed in relation to trailer frame (15). The size of theair spring (85′) and geometry of its mounting points is selected tosuit. FIG. 19 is a schematic of the air circuit system of thisembodiment.

The air spring or second airbag (85′) ensures that adequate load isapplied to the drawbar whilst travelling and in emergency brakingsituations. The load applied to the draw bar is maintained to less thanthe tow bar capacity of the tow vehicle (say 250-300 kg) whilstlowering. Importantly, the tow vehicle is not overloaded in the event ofair system failure, as may occur with a steel spring and mechanicallock. The air spring or airbag (85′) for the draw bar is connected intothe same air circuit with one suspension airbag (44) and they aretherefore held at common pressure forming a fail safe system. If failureoccurs, i.e if air circuit pressure is lost in this part of thepneumatic system, one side of the trailer would lower to the ground asairbag (44) deflates, and the draw bar would hinge as second airbag(85′) deflates. The trailer frame would contact the road and the driverof the vehicle would be soon made aware of the situation, yet thevehicle's tow bar would not be overloaded.

Advantageously, this avoids the disadvantage of the first embodiment ofthe pivoting arrangement, as in the first embodiment, in the event ofactuation means (air bag) or system failure, the rear of the trailerwould contact the ground but the draw bar would not hinge, resulting inapproximately half of the gross trailer mass being applied to the towvehicle.

In the second embodiment, a single air system with a fail-safe mode istherefore used to both raise and lower the trailer, to allow pivoting orhinging of the draw bar and to lock the draw bar in a straight, towing,position. Advantageously, the whole raising and lowering operation maytherefore be automatically controlled on a single system. The fail-safeaspect of the system is particularly of note where the actuation meansis the first airbag, that is, the system does not have a mirror imageairbag on the other side of the trailer. However, the fail-safe systemis also relevant where the actuation means includes a mirror imageairbag on the other side of the trailer, as shown in FIGS. 16 to 19.

FIG. 19 shows a pneumatic circuit or air system circuit (90) having thefirst airbag (44) and second airbag (85′) on a single circuit which maybe isolated by a first solenoid operated isolating valve (93). Thuspressure in the first and second airbags (44, 85′) is equal anddepressurisation of the first air bag (44) (e.g. through a leak orfailure) will also depressurise second airbag (85′) as described above.

The mirror image airbag could be directly connected (not shown) with thefirst and second airbags such that it also has the same pressure,however preferably the mirror image airbag (44′) is isolated behind asecond solenoid operated isolating valve (93′), as this increases thestability of the trailer under load and while towing. Loss of pressurein either of the first and second airbags (44, 85′) results in the frontand one side of the trailer lowering, avoiding load on the towbar andmaintaining enough stability for the driver to pull over. Loss ofpressure in the mirror image airbag (44′) results in a slight drop onthat side and slight increase in the vehicle's tow bar load, howeveragain stability is maintained, as pressure is not lost in the first andsecond airbags (44, 85′), and the trailer can be maintained in areasonable towing position until the problem is rectified. Thus there isprovided a system which is simple, cost-effective and easy to operate,and the whole raising and lowering operation can be automaticallycontrolled on a single system. In the embodiment of FIG. 19, first andsecond isolating valves (93, 93′) are opened to allow pressurised airfrom a compressor (91) (which has an associated filter (91 a) and isbehind a check valve (92)) to fill the airbags (44, 44′, 85′). Wheninflated, the first and second isolating valves (93, 93′) are closed toretain pressurised air in the air bags (44, 44′, 85′).

To deflate the airbags (44, 44′, 85′), the first and second isolatingvalves (93, 93′) are opened, as is a third solenoid operated isolatingvalve (94) which vents the pressurised air to atmosphere This valve isalso referred to as the venting valve (94). The third isolating valve orventing valve (94) is closed when inflating the airbags (44, 44′, 85′)so that pressurised air passing from the compressor (91) through thecheck valve (92) does not vent to atmosphere via third isolating valve(94), but rather passes through open first and second isolating valves(93, 93′).

Also located in the circuit (90) is a compressor cut-off pressure switch(95) operable to cut-off the compressor (91) in response to a limitpressure or an unacceptable pressure detected between check valve (92)and first, second and third isolating valves (93, 93′, 94).

The check valve (92) ensures that the compressor starts up under noload, and isolates the circuit when the compressor 91 is not running.

Optionally, an air tank (97) may be provided behind a fourth solenoidoperated isolating valve (96). The air tank (97) may be filled withpressurised air which is stored until it is necessary to raise thetrailer (10) by inflating air bags (44, 44′). Release of the store ofpressurised air from the tank (97) provides an initial injection to thecircuit (90) and reduces the time required to raise the trailer (10).Preferably, the compressor (91) runs while travelling, with the first,second and third isolating valves (93, 93′, 94) closed and the fourthisolating valve (96) open to allow the tank (97) to be filled. Thecompressor (91) may be powered by the towing vehicle or by other means.Once the tank 97 has been filled at the required pressure, compressorcut-off pressure switch (95) operates to cut-off the compressor andfourth isolating valve (96) is closed.

Preferably, the air tank (97) is incorporated into the trailer chassisor frame (15), for example being formed by chassis hollow sectionmembers required for structural rigidity. Making the e.g. square hollowsection member(s) air tight will save weight and cost, as well asmaximise load space, in comparison to a separate tank or bottle.Multiple hollow sections could be connected to form a distributed ‘tank’or reservoir.

Once the trailer bed (16) has been lowered to the ground (7) the load(6) may easily be removed. To raise the trailer back to the towingposition, airbags (44, 44′, 85′) are re-inflated. As airbags (44, 44′)are inflated, so is airbag 85′ and draw bar (12) returns to a horizontalposition.

FIG. 18 shows a draw bar (12) stowed in an upright position, allowingfor an unhitched trailer to be positioned in a smaller area. This isuseful for storage of the trailer (e.g. in a garage) or for parking thetrailer at a race event, whether or not the race car remains loaded. Theairbag 85′ is disconnected from the connecting bracket (70). Provisionof hole (77) provides a convenient method of locking draw bar (12) in anupright position by insertion of a pin (not shown) to hold the draw bar(12) in place.

Preferably, and as shown in FIGS. 14 and 15, a torsion spring (52)having a manual release (53) provides arrest means (50) to prevent thewheel (6′) of a race car from rolling backwards off the trailer. Thishelps to prevent the race car from rolling off the trailer when thetrailer frame (15) is in the intermediate position between raised/towingposition and lowered/unloading position. FIG. 14 shows the wheel (6′) ofthe race car rolling forward in the direction of the arrow onto thetrailer, rolling over the arrest means (50) and depressing a chock (51)connected to or part of torsion spring (52). In FIG. 15, the wheel (6′)has passed beyond chock (51), which springs back into position as achock (51) behind wheel (6′). Wheel (6′) is thereby prevented frommoving backward in the direction of the arrow. Manual release (53) isbraced on trailer frame (15) and may be manually activated (ie rotated)to rotate torsion spring (52) and release the chock (51) in order tounload the race car.

1-23. (canceled)
 24. A trailer including: i) a draw bar; ii) a trailerframe supporting a trailer bed; iii) an arm including a first pivotmount; iv) an axle pivotally connected to the arm at the first pivotmount; v) an actuating means actuatable to exert a force on the armrelative to the trailer frame; wherein the axle includes at least oneassociated wheel and the wheel has a plane of rotation in which thewheel rotates when traveling in a forward direction, and the actuatingmeans is located substantially in the plane of rotation; whereby thetrailer bed may be raised or lowered by exerting a force on the armrelative to the trailer frame.
 25. A trailer according to claim 24,wherein the first pivot mount is located inwardly of the wheel.
 26. Atrailer according to claim 24, wherein the actuating means exerts theforce on the arm at a location substantially in the plane of rotation.27. A trailer according to claim 24, wherein the actuating means exertsthe force on the arm at a location forward of the wheel.
 28. A traileraccording to claim 24, wherein the actuating means exerts the force onthe arm at a location rearward of the wheel.
 29. A trailer according toclaim 24, wherein the arm is pivotally connected to the axle at alocation inwardly of the wheel and the actuating means acts on a portionof the arm at a location substantially in the plane of rotation.
 30. Atrailer according to claim 24, wherein the trailer frame includes asecond pivot mount, the arm being pivotally movable relative to thetrailer frame about the second pivot mount.
 31. A trailer according toclaim 30, wherein the second pivot mount is located substantially in theplane of rotation.
 32. A trailer according to claim 30, wherein theactuating means exerts the force on the arm at a location forward of thesecond pivot mount.
 33. A trailer according to claim 30, wherein theactuating means exerts the force on the arm at a location rearward ofthe second pivot mount.
 34. A trailer according to claim 24, wherein thearm includes at least two portions that are angled relative to eachother when projected on the plane of rotation.
 35. A trailer accordingto claim 24, wherein the arm includes at least two portions that areangled relative to each other when projected onto a substantiallyhorizontal plane perpendicular to the plane of rotation.
 36. A traileraccording to claim 24, wherein the arm includes at least a first sectionand a second section, the first and second sections being in slideableengagement.
 37. A trailer according to claim 24, wherein the trailerframe includes a third pivot mount located higher than and rearward ofthe second pivot mount, the actuating means pivotally mounted to thethird pivot mount and actuatable to exert a force on the arm resultingin rotation of the arm about the second pivot mount.
 38. A traileraccording to claim 24, wherein the trailer frame includes a fixed pointlocated higher than and forward of the second pivot mount, the actuatingmeans actuatable to exert a force between the fixed point and the arm,resulting in rotation of the arm about the second pivot mount.
 39. Atrailer according to claim 38, wherein the fixed point is provided by abracket.
 40. A trailer according to claim 24, wherein the actuatingmeans includes a first airbag.
 41. A trailer according to claim 24,further comprising a draw bar pivot mount, the draw bar pivotallyconnected to trailer frame via draw bar pivot mount.
 42. A traileraccording to claim 24, wherein the actuating means includes a firstairbag, the trailer further including a draw bar pivot mount, the drawbar pivotally connected to trailer frame via draw bar pivot mount andfurther including a spring and an air valve, the valve being operable todeflate first airbag and the spring biasing the draw bar towards atowing position.
 43. A trailer according to claim 24, wherein theactuating means includes a first airbag, the trailer further including adraw bar pivot mount, the draw bar pivotally connected to trailer framevia draw bar pivot mount and further including a draw bar bracketmounted on the draw bar, a connecting bracket mounted on the trailerframe, and a second airbag extending between the draw bar bracket andthe connecting bracket, the second airbag when inflated positioning thedraw bar in a towing position.
 44. A trailer according to claim 43,wherein the first and second airbags include a common first isolatingvalve and a common venting valve, whereby they are held at a commonpressure.
 45. A trailer according to claim 24, further comprising brakesassociated with the wheel and a safety brake interlock switch operableto prevent the wheel from turning when the draw bar is not in a towingposition.
 46. A trailer according to claim 24, wherein the draw bar isconfigured to couple the trailer to a tow vehicle and the trailer bed isconfigured to be lowered flat to the ground for loading and unloadingwithout decoupling the trailer from the tow vehicle.